Insulator to Semimetal Transition in Graphene Oxide

Eda, Goki; Mattevi, Cecilia; Yamaguchi, Hisato; Kim, Hokwon; Chhowalla, Manish

doi:10.1021/jp9051402

Cited by 594 publications

(499 citation statements)

References 28 publications

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“…As the room-temperature conductivity approaches saturation after high-temperature annealing, the characteristic hopping energies of the two coals converge and approach a minimum. The values here reported are in good agreement with those for single flake rGO devices (20−140 K 1/3 depending strongly on the degree of reduction) 43,44 and a-C (from 220 K 1/4 for σ = 10 −5 S/m to 87 K 1/4 for σ = 10 0 S/ m). 45,46 This demonstrates that in addition to possessing similar chemical properties, including the sp 2 domain size and amount of disorder, these properties result in the same conduction mechanism for the natural sourced carbon material and comparable synthetic materials such as a-C and rGO.…”

Section: * S Supporting Informationsupporting

confidence: 87%

Rethinking Coal: Thin Films of Solution Processed Natural Carbon Nanoparticles for Electronic Devices

2016

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Disordered carbon materials, both amorphous and with long-range order, have been used in a variety of applications, from conductive additives and contact materials to transistors and photovoltaics. Here we show a flexible solution-based method of preparing thin films with tunable electrical properties from suspensions of ball-milled coals following centrifugation. The as-prepared films retain the rich carbon chemistry of the starting coals with conductivities ranging over orders of magnitude, and thermal treatment of the resulting films further tunes the electrical conductivity in excess of 7 orders of magnitude. Optical absorption measurements demonstrate tunable optical gaps from 0 to 1.8 eV. Through low-temperature conductivity measurements and Raman spectroscopy, we demonstrate that variable range hopping controls the electrical properties in as-prepared and thermally treated films and that annealing increases the sp 2 content, localization length, and disorder. The measured hopping energies demonstrate electronic properties similar to amorphous carbon materials and reduced graphene oxide. Finally, Joule heating devices were fabricated from coal-based films, and temperatures as high as 285°C with excellent stability were achieved. KEYWORDS: Coal, amorphous carbon, organic semiconductors, thin films, solution processing C arbon has long been known as one of the most chemically versatile elements. As a result, carbonaceous materials have been of technological interest for their wide range of electronic propertiesresulting in materials ranging from low cost conducting materials such as graphite and carbon black, to semiconducting fullerenes and carbon nanotubes, and to insulating diamond and diamond-like carbon. Specifically, carbon black, carbon filaments, and other carbon materials are used in electrodes, conductivity additives, and electromagnetic reflectors. 1 Graphitic materials 2 and amorphous carbon (a-C) 3,4 are the leading and a promising candidate, respectively, for anode materials in lithium ion batteries. Amorphous carbon has also been used in the manufacturing of transistors 5,6 and photovoltaic devices, 7,8 and nanostructured graphitic materials (such as graphene and reduced graphene oxide) have gained significant attention for applications including in photovoltaics, 9−11 transparent conductive membranes, 12−16 and Joule heating devices. 17−19 Despite decades of research on synthetically processed carbon materials, facile, tunable, 20 low-temperature, solution processing methods remain elusive. Carbon black synthesis requires temperatures as high as 2000°C, 21 and a-C is typically deposited by plasma-enhanced chemical vapor deposition (CVD) 22,23 although aerosol-assisted CVD has recently been demonstrated. 8 While extensive research has been conducted to develop solution-based methods of graphene deposition, rGO films remain several orders of magnitude less conductive than CVD graphene. 16,24,25 In contrast to the widely studied world of synthetic carbonaceous materials, the optical...

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Section: * S Supporting Informationsupporting

confidence: 87%

Rethinking Coal: Thin Films of Solution Processed Natural Carbon Nanoparticles for Electronic Devices

2016

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“…Figure 5 show that the transport is only described by p =1/2 model. In previously reported data on single layer RGO devices, 2D Mott VRH (p =1/3) was reported [11,[19][20]. This may be due to limited temperature range of the data where it might be possible to fit the same data with both T -1/2 and The calculated value of ξ is about 3.5 nm which is comparable to the calculated GQD sizes, indicating strong localization of the wave function inside each graphitic domain.…”

Section: Theoretical Studies Of Qd Arrays By Middleton and Wingreen (supporting

confidence: 59%

“…All these studies clearly suggest that RGO should behave as a two dimensional array of graphene quantum dots (GQD), which should be verified from low temperature electron transport measurements. However, previous electrical transport studies of RGO in limited temperature range show 2D Mott variable range hopping (VRH) [11,[19][20] which is not expected from a QD array model. Additionally, Mott VRH neglects the Coulomb interaction between localized graphitic domains which may be significant at low temperature as recent study of individual 10 nm sized graphene quantum dots show room temperature Coulomb blockade (CB) [21,22].…”

Section: Introductionmentioning

confidence: 81%

Coulomb blockade and hopping conduction in graphene quantum dots array

2011

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We show that the low temperature electron transport properties of chemically functionalized graphene can be explained as sequential tunneling of charges through a two dimensional array of graphene quantum dots (GQD). Below 15 K, a total suppression of current due to Coulomb blockade through GQD array was observed. Temperature dependent current-gate voltage characteristics show Coulomb oscillationswith energy scales of 6.2-10 meV corresponding to GQD sizes of 5-8 nm while resistance data exhibit an Efros-Shklovskii variable range hopping arising from structural and size induced disorder.

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“…The deviation from linear fit at the lower temperautre regime can be explained by the contribution of the field-driven conduction without thermal activation [46][47][48] . However, the GO sheet with a lower O/C composition of 0.32 showed a deviation from the linear fit (that is, 2D-VRH model) at all examined V ds and the temperature dependence of the s min at the higher temperature regime can be fitted reasonably well with the Arrhenius model, suggesting that thermally excited carriers begin to dominate electrical conduction 49 . Based on the transport properties of the GO sheets, we can conjecture that the bandgap energy of GO was narrowed down as the O/C composition decreased from 0.80 to 0.32, which is in agreement with the UV-vis measurement.…”

Section: Synthesis Of the Go Sheetsmentioning

confidence: 81%

Monolithic graphene oxide sheets with controllable composition

et al. 2014

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Graphene oxide potentially has multiple applications and is typically prepared by solutionbased chemical means. To date, the synthesis of a monolithic form of graphene oxide that is crucial to the precision assembly of graphene-based devices has not been achieved. Here we report the physical approach to produce monolithic graphene oxide sheets on copper foil using solid carbon, with tunable oxygen-to-carbon composition. Experimental and theoretical studies show that the copper foil provides an effective pathway for carbon diffusion, trapping the oxygen species dissolved in copper and enabling the formation of monolithic graphene oxide sheets. Unlike chemically derived graphene oxide, the as-synthesized graphene oxide sheets are electrically active, and the oxygen-to-carbon composition can be tuned during the synthesis process. As a result, the resulting graphene oxide sheets exhibit tunable bandgap energy and electronic properties. Our solution-free, physical approach may provide a path to a new class of monolithic, two-dimensional chemically modified carbon sheets.

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Insulator to Semimetal Transition in Graphene Oxide

Cited by 594 publications

References 28 publications

Rethinking Coal: Thin Films of Solution Processed Natural Carbon Nanoparticles for Electronic Devices

Rethinking Coal: Thin Films of Solution Processed Natural Carbon Nanoparticles for Electronic Devices

Coulomb blockade and hopping conduction in graphene quantum dots array

Monolithic graphene oxide sheets with controllable composition

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